1. Field of the Invention
The present invention relates to an apparatus for retracting or shifting backward an interchangeable photo-taking lens used in a photo-taking device such as, for example a photographic camera.
2. Description of the Prior Art
In a lens shutter camera having an automatic focusing capability, a photo-taking lens is set to a predetermined initial position, for example, either the infinity position or the closest distance position, by a predetermined mechanism when the photo-taking has been completed and can, when a photographer depresses the release button through a first stroke of depression, be either extended or retracted from this predetermined initial position by a drive means on the basis of a result of focus detection to form an image of a target object to be photographed on a film plane automatically. In a certain type of prior art lens shutter cameras, the photo-taking lens extended for the purpose of focusing is arranged so as to be retracted towards the predetermined initial position by a shutter charge mechanism, operatively associated with a film winding operation, when and after the photo-taking has been completed.
In another type of prior art lens shutter cameras, the photo-taking lens then extended by the use of a focusing drive means for focusing use is arranged so as to be retracted towards the predetermined initial position by the use of the same drive means when and after the actual photo-taking has been completed. Also, in a lens shutter camera having a built-in electronic flash device and a photo-taking lens selectively switchable two focal lengths (for example, standard and telephoto), arrangement is made to shorten the length of the photo-taking lens by switching over to the standard focal length in operatively associated relationship with the accommodation of a light emitting portion of the built-in flash device which, when photo-taking, pops up, thereby rendering the camera to be compact such as disclosed in, for example, the Japanese Laid-open Patent Publication No. 60-78432.
However, in a prior art single-reflex camera having a lens interchangeable capability, the interchangeable photo-taking lens remains extended to a position to which it has been moved for the purpose of actual photo-taking and, particularly where the camera is mounted with an interchangeable lens of either macro type or telephoto type, the photo-taking lens is very long if the photo-taking lens remains extended and, accordingly, when it comes to the transportation of the camera from place to place, the extended lens poses a problem in that the portability of the camera as a whole is reduced.
In order to obviate the above discussed inconvenience, the lens then extended has to be manually retracted in readiness for the transportation of the camera.
In any one of the first and second mentioned conventional lens shutter cameras, the focusing lens is first retracted to a predetermined position and, from this position, the focusing lens is extended for focusing purpose. This is possible because the lens is non-interchangeably mounted in the camera. On the contrary thereto, in the single-reflex camera having a lens interchangeable capability, it often occurs that, while the lens is removed from the camera, the focusing lens may move to any indefinite position, and the lens is not arranged to move to any position after the photo-taking. Also, in the lens shutter camera of the type having the two selectively switchable focal lengths, the switching is effected only to the position at which the lens assumes the shorter focal length, and the lens is in no way retracted.